The invention relates to a disc-record player comprising pressure means for pressing a disc onto a turntable, and a mandril which is coaxial with the turntable and which engages the center hole of the disc. The pressure means comprises rollers which can deflect elastically in a radial direction relative to the axis of rotation of the turntable and which urge the disc against the turntable.
A disc-record player of this type is disclosed in French Patent Specification 2.078.456. In such a known disc-record player the pressure means is integral with the mandril, the rollers being urged radially outwards by an elastic material through apertures in the wall of the mandril. As a result of this movement the rollers act against the edge of the center hole of a disc on the turntable, thereby exerting such a force on the edge of the center hole of the disc that the disc is urged against the turntable. If the edge of the center hole of the disc is not defined accurately, for example due to the presence of burrs formed during manufacture of the disc, the pressure means of the known disc-record player will exert different forces by the rollers on the edge of the center hole, so that an inadequate and/or irregular pressure is exerted on the disc. In practice the pressure means of the known disc-record player is therefore only suitable for use in low-quality disc-record players where a less accurate operation of the pressure means is permissible. In particular, such a pressure means is not suitable for use with optical discs read by means of laser light, for example of the Compact Disc type, in which discs the edge of the center hole is not defined accurately in a vertical direction due to the method of manufacturing these discs.
The known disc-record players for playing optically readable discs employ a pressure means which acts on the disc at some radial distance from the center hole. The force required for pressing down is obtained by cooperation between a magnetic material in the pressure means and an iron ring on the turntable. However, this gives rise to a magnetic stray field which may disturb the operation of other actuators of the disc-record player in the proximity of the pressure means, for example the focusing actuator of the optical head of the player.
Another known possibility is the use of a pressure means arranged on a resilient arm, whose resilience provides an adequate pressure. However, during playing this results in the turntable spindle being continually subjected to an axial load which produces friction and gives rise to an additional torque on the drive motor of the turntable.